1. Field of the Invention
The present invention relates to fiber optic connectors and mass interconnect or interface devices. More particularly, the invention relates to a new and novel assembly for a fiber optic connector that increases the cycle life of that fiber optic connector when used in a mass interconnect device.
2. Description of the Related Art
An interface or mass interconnect device includes a receiver and an Interface Test Adapter (ITA) that are mated together to form connections between connectors mounted in modules in the receiver and ITA. An example of one such mass interconnect or interface device is disclosed in U.S. Pat. No. 4,329,005. Commercially available examples of such interface devices include, but are not limited to, Virginia Panel Corporation's Series 90 and Gemini interface devices. In such interface devices, it has often been desirable to include multiple types of electrical connectors in a single interface. To do so, one may incorporate separate modules for each type of connector or may create modules that accommodate multiple types of connectors.
Due to recent advances in technology, it has become desirable to include fiber optic connectors in such interface devices. Including both fiber optic connectors and electrical connectors together in a single interface device, however, has raised new problems. One such problem is that fiber optic connectors require a shorter travel distance to make a connection than do some other types of connectors. When fiber optic connectors are used in an interface device with other types of connectors, this difference in required travel distances can result in unnecessarily strong forces being applied to the tips of the fiber optic cables being connected. Such unnecessarily high forces can cause damage to the tips of the fiber optic cables. Further, some fiber optic connectors require axial positioning, which is not necessary for many other types of connectors.
Thus, conventional fiber optic connectors suffer from the problems of having limited cycle lives between polishings and/or limited repolishings before needing to be replaced. Connectors such as the M29504 type termini, which have a two thousand mating cycle specification, have only a very limited amount of travel (0.030″) for the termini to work. This limited travel reduces the number of times the termini can be re-polished before needing to be replaced. These termini additionally suffer from the problems of high cost and difficulty in obtaining good termini performance.
In contrast, termini having significant travel (0.090″), such as a TFOCA type termini, have a five hundred mating cycle specification, but they can be re-polished and then work for another 500 cycles. By observing the termini tip under a microscope, however, the inventors have found that the fiber-cladding, material that surrounds the core of the optical fiber, was flaking apart and thereby making the termini fail. The cladding fails due to material surface fatigue, like a bearing surface without lubrication.
During the connector mating the two termini surfaces are in contact and exposed to limited motion perpendicular to the termini axis. During this motion, point contacts are created with a significant force (1.5 lb) applied at the same time. This causes very localized high surface pressure that results in the fiber-cladding material failure.